Kanishka's Rise to Power
The Kushana Empire was established in ancient India by Kujala Kadphises. He was succeeded by his son Wema Kadphises, who consolidated a strong Kushana Empire in India. But for a long time with the death of Wema Kadphises the line of Kushana kings bearing the surname of Kadphises vanished. Kanishka I formed a different line of Kushana kings. However, historians in the later years discarded the view on the basis of the discovery of "Kamra" inscription of Vashiska Kushana and the new interpretation of "Mathura" or "Mot" inscription.
Though historians believe the kinship of Wema Kadphises and Kanishka, yet the relationship between these two kings is yet not discovered. Again, some other historians have suggested that "Kadphises was not actually a surname, rather it was a title used by Kujala and his son Wema. Kanishka, the successor of Wema had discarded the use of title, which was used by his predecessors". Historians have opined that "Kadphises" is a derivation from the Indian word "Katpais", which means "an honourable person". Since it was not a family surname, Kanishka did not use it. Dr. B.N Mukherjee has discovered the "Kamra inscription" of Vashiska Kushana, successor of Kanishka I, where he discovered that Vashiska was the descendant of Kujala Kadphises. Moreover the Mot inscription found near Mathura contained a statue of Wema Kadphises. Wema was part of the Devakula, to which Kanishka I also belonged. Another inscription in Mathura was discovered which delineated that Hubiskha's ancestor was Wema Kadphises. As Hubiskha was a direct descendant of Kanishka I, so Kanishka I appeared to belong in the same family line to which Kujala and Wema Kadphises also belonged.
Ancestry of Kanishka
However there are many scholars who have approached different theories regarding the ancestry of Kanishka. Those who believe Kanishka and Wema Kadphises belonged to dissimilar kinship have put forward several arguments in favour of their theories. According to them, Kanishka I promulgated a new era and issued new mintage, which was completely different from the Kadphises. Moreover Kanishka seemed to have built his kingdom by his own conquests. The earliest records of Kanishka I are found in the areas of Sarnath in Uttar Pradesh. Probably he was the governor of that region.
According to this group of historians, Wema ruled mainly in the Northwest and U.P and Mathura might have formed the underlying parts of the Empire of Wema Kadphises. So they surmised it that Kanishka was the viceroy or the subordinate king of Wema Kadphises. After the death of Wema, when the struggle for supremacy started among his successors, Kanishka emerged successful in the region of U.P. Kanishka supplanted his rivals and consolidated his position in U.P. From U.P, Kanishka extended his sway to Punjab, Sind and Northwestern India. However the Kushana ancestry of Kanishka could be determined from his Central Asian dress and features depicted in a portrait found in Mathura. But, whatever confusion and contradiction is there regarding the origin and ancestry of Kanishka I, views of Dr. B.N. Mukherjee generally prevails.